Wiz Khalifa and his video "See You Again" hit a milestone this week, becoming the tenth video ever to cross 1 billion views on YouTube. At 184 days, "See You Again" is the second-fastest video to hit 1 billion in YouTube history (after “Gangnam Style”), and the quickest of the past year. Khalifa and Charlie Puth’s tribute to the late Paul Walker joins what appears to be an ever-accelerating trend in billion-view videos.

For ten years, the Billion View Club was one of the most exclusive circles on YouTube, but in 2015, things changed. At the start of this past June, only two videos had reached that echelon. But in just the past six months, EIGHT additional videos crossed the mark. Here are the videos ranked by views with a graph showing the trajectory of these videos over the past five years.

As you can see below, the rate at which videos are accelerating to this milestone appears to be increasing as well. The average number of days it took for a video to cross 1 billion is 484 days, but of the videos that have done it, the three most recent crossed it at an average of 241 days.

Other fun facts:

In what may be a surprise to Americans, Enrique Iglesias' "Bailando" became the second non-English video to cross 1 billion views. According to YouTube Music Insights, one-third of Iglesias' views come from Mexico, Colombia, and Argentina alone.